The present invention relates generally to the field of sound devices.
Powered sub woofer device has been traditionally known that it would (1) filter electronic signals that were input to it with low pass filter, (2) amplify low-frequency range electronic signals with power amplifier, and (3) operate its speaker. U.S. Patent Publication No. 2006/0005694 has published the technology that would (1) separate electronic signals that were input from one single input terminal into high frequency range and low frequency range with crossover filter, (2) operate tweeter with high frequency range electronic signals that were output from there, (3) amplify low frequency range electronic signals, and (4) operate its woofer.
There, however, was an issue that the device had to prepare both powered full range speaker and powered sub woofer and differentiate its use, for the following reasons:                1) Powered sub woofer could only play low frequency range;        2) Powered full range speaker could only play full range; and        3) Desired frequency ranges for playback were different depending on surrounding environment and conditions.        